| Message ID | 20220725122120.309236-5-eesposit@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Refactor bdrv_try_set_aio_context using transactions | expand |
Am 25.07.2022 um 14:21 hat Emanuele Giuseppe Esposito geschrieben: > This enables the caller to use the same transaction to also > keep track of aiocontext changes. > > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> What you're really doing here is factoring out the recursive phase. However, the factored out function is never used from anywhere else, so I don't understand the purpose of this patch. It feels like an unnecessary complication of the code. The commit message is unclear to me, too: Who is the caller of bdrv_child_try_change_aio_context() that it mentions, and why does it make a difference to it how the code is organised internally? Is this some artifact of changes you made and we don't need it any more now? > block.c | 31 ++++++++++++++++++++++++------ > include/block/block-global-state.h | 5 +++++ > 2 files changed, 30 insertions(+), 6 deletions(-) > > diff --git a/block.c b/block.c > index c02a628336..221bf90268 100644 > --- a/block.c > +++ b/block.c > @@ -7643,17 +7643,16 @@ int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, > * For the same reason, it temporarily holds also the new AioContext, since > * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too. > */ > -int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, > - BdrvChild *ignore_child, Error **errp) > +int bdrv_child_try_change_aio_context_tran(BlockDriverState *bs, > + AioContext *ctx, > + BdrvChild *ignore_child, > + Transaction *tran, > + Error **errp) As mentioned above, this is never used anywhere else than from bdrv_child_try_change_aio_context(), so if we want to keep the patch, it should be static at least. Maybe find a better name, too, because all of the transaction related operations are in the caller. The function comment is not accurate any more either because it described the whole of bdrv_child_try_change_aio_context(), while this function only contains the recursive part. Kevin
Am 07/10/2022 um 18:10 schrieb Kevin Wolf: > Am 25.07.2022 um 14:21 hat Emanuele Giuseppe Esposito geschrieben: >> This enables the caller to use the same transaction to also >> keep track of aiocontext changes. >> >> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> > > What you're really doing here is factoring out the recursive phase. > However, the factored out function is never used from anywhere else, > so I don't understand the purpose of this patch. It feels like an > unnecessary complication of the code. > > The commit message is unclear to me, too: Who is the caller of > bdrv_child_try_change_aio_context() that it mentions, and why does it > make a difference to it how the code is organised internally? So this was an initial (mis)understanding from what Vladimir suggested, where everything should be part of a single transaction. If you want, I can drop this. Thank you, Emanuele > > Is this some artifact of changes you made and we don't need it any more > now? > >> block.c | 31 ++++++++++++++++++++++++------ >> include/block/block-global-state.h | 5 +++++ >> 2 files changed, 30 insertions(+), 6 deletions(-) >> >> diff --git a/block.c b/block.c >> index c02a628336..221bf90268 100644 >> --- a/block.c >> +++ b/block.c >> @@ -7643,17 +7643,16 @@ int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, >> * For the same reason, it temporarily holds also the new AioContext, since >> * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too. >> */ >> -int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, >> - BdrvChild *ignore_child, Error **errp) >> +int bdrv_child_try_change_aio_context_tran(BlockDriverState *bs, >> + AioContext *ctx, >> + BdrvChild *ignore_child, >> + Transaction *tran, >> + Error **errp) > > As mentioned above, this is never used anywhere else than from > bdrv_child_try_change_aio_context(), so if we want to keep the patch, it > should be static at least. > > Maybe find a better name, too, because all of the transaction related > operations are in the caller. > > The function comment is not accurate any more either because it > described the whole of bdrv_child_try_change_aio_context(), while this > function only contains the recursive part. > > Kevin >
diff --git a/block.c b/block.c index c02a628336..221bf90268 100644 --- a/block.c +++ b/block.c @@ -7643,17 +7643,16 @@ int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx, * For the same reason, it temporarily holds also the new AioContext, since * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too. */ -int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, - BdrvChild *ignore_child, Error **errp) +int bdrv_child_try_change_aio_context_tran(BlockDriverState *bs, + AioContext *ctx, + BdrvChild *ignore_child, + Transaction *tran, + Error **errp) { - Transaction *tran; GHashTable *visited; int ret; - AioContext *old_context = bdrv_get_aio_context(bs); GLOBAL_STATE_CODE(); - /* Recursion phase: go through all nodes of the graph */ - tran = tran_new(); visited = g_hash_table_new(NULL, NULL); if (ignore_child) { g_hash_table_add(visited, ignore_child); @@ -7661,6 +7660,26 @@ int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp); g_hash_table_destroy(visited); + return ret; +} + +/* + * See bdrv_child_try_change_aio_context_tran for invariants on + * AioContext locks. + */ +int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, + BdrvChild *ignore_child, Error **errp) +{ + Transaction *tran; + int ret; + AioContext *old_context = bdrv_get_aio_context(bs); + GLOBAL_STATE_CODE(); + + /* Recursion phase: go through all nodes of the graph */ + tran = tran_new(); + ret = bdrv_child_try_change_aio_context_tran(bs, ctx, ignore_child, tran, + errp); + /* Linear phase: go through all callbacks collected in the transaction */ if (!ret) { diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h index ceecf0aa8e..1bd445b507 100644 --- a/include/block/block-global-state.h +++ b/include/block/block-global-state.h @@ -234,6 +234,11 @@ bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx, Error **errp); int bdrv_child_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, BdrvChild *ignore_child, Error **errp); +int bdrv_child_try_change_aio_context_tran(BlockDriverState *bs, + AioContext *ctx, + BdrvChild *ignore_child, + Transaction *tran, + Error **errp); int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz); int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo);
This enables the caller to use the same transaction to also keep track of aiocontext changes. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> --- block.c | 31 ++++++++++++++++++++++++------ include/block/block-global-state.h | 5 +++++ 2 files changed, 30 insertions(+), 6 deletions(-)